import std;

void main() {
    const s = readln.chomp;
    const n = s.length;
    int ret = 0;
    foreach(i; 0 .. n - 2) {
        if ((s[i] == s[i + 1] && s[i] != s[i + 2]) || (s[i + 1] == s[i + 2] && s[i] != s[i + 1])) {
            ret++;
        }
    }
    writeln(ret);
}